The invention relates to an apparatus for, and a method of, destacking a stack of flat articles, of the general type disclosed in WO 00/46135 and corresponding U.S. Pub. No. 2001/0054788. As there disclosed, a stack of flat articles, in particular printed products, rests on a bearing surface and is destacked from above by a separating arrangement. The separating arrangement is supported on the stack from above by means of a load bearing structure, with the result that its vertical distance from the stack is always constant during destacking.
The separating arrangement as disclosed in the above documents is used to separate out individual articles from the stack and to transfer them to a removal arrangement in the form of a belt conveyor. The separating arrangement comprises a sucker by means of which the article which is located at the top of the stack in each case is attached by suction at one end. A pusher then grips beneath the article and pushes it out of the stack in the direction of the removal arrangement. By virtue of articles being periodically separated out, an imbricated stream of partially overlapping articles is produced on the belt conveyor. The removal arrangement can be pivoted in the manner of a rocker, with the result that it is possible for the height of the region in which articles can be received to be adapted to the current stack height and for the articles to be pushed onto the belt conveyor essentially in their own plane. The removal arrangement is connected to the separating arrangement via the load-bearing structure, with the result that the height adaptation likewise takes place passively by sensing of the current stack height.
The above referenced documents propose that, during destacking or once destacking has taken place, a further stack of flat articles is fed to the region of the bearing means from beneath, i.e. in the normal direction to the bearing surface. The further stack here is located on a further bearing means, which is oriented parallel to the first-mentioned bearing means and is moved in the normal direction thereto. In order to ensure a continuous changeover from one stack to the next and thus a gap-free imbricated stream, it is necessary for the bearing means located between the two stacks to be removed in a suitable manner. As an alternative, the above documents propose using individual products in an imbricated stream in a plane which runs parallel to the bearing surface of the stack, but is located therebeneath. It is also the case with this variant that the bearing surface between the two sub-stacks has to be removed at a given time. This can only be realized with high design related outlay.
DE 1947095 B2 and U.S. Pat. No. 3,776,544 disclose an apparatus which is intended for discharging flat articles and in the case of which individual stacks are supplied on a conveying belt and removed from beneath. For this purpose, the stack, in the destacking position, is tilted by a barrier which is inclined in the vertical, and the respectively lowermost article of the stack is drawn out of the stack by a belt conveyor, while the articles located thereabove are retained by the barrier. The problem here is that the weight of the entire stack always bears on the article which is to be removed, the latter thus being subjected to mechanical stressing during removal.
The object of the invention is thus to provide an apparatus for, and a method of, destacking a stack of flat articles in the case of which the destacking follows from above in a manner which does not adversely affect the articles, and the operation of feeding the stack is simplified in relation to the known apparatuses.